Passo Tratto Spino

Overview

Passo Tratto Spino is a hors catégorie (HC) climb, the hardest grade there is, and it earns that label the honest way — through sheer length. Over 22.3 km it climbs from a valley floor at 201 m to a summit at 1725 m, a net gain of 1524 m. The average gradient sits at a demanding 6.83%, and when you account for the small dips and false flats along the way, the total ascent works out to 1617 m — roughly 93 m more than the net figure. This is a climb that asks for patience first and power second.

How the Gradient Unfolds

A 6.83% average across 22.3 km is deceptively hard, because averages hide the spikes. Here the sharpest pitch reaches 18.08% — nearly triple the mean — so the road is anything but uniform. Expect the grade to swing above and below that 6.83% line repeatedly, with the steepest ramps hitting where fatigue is already deep. The gap between the 1617 m of total ascent and the 1524 m net gain tells you there are brief reliefs — short descents or flatter shelves — that break the rhythm but never long enough to fully recover. Treat every easing as a chance to reset your breathing, not to attack.

Pacing Notes

On a climb this long, pacing is everything. The single biggest mistake is chasing the 18.08% ramps out of the saddle and blowing your effort before the halfway mark. Anchor your ride to your FTP and aim to hold a steady, sustainable percentage of it for the full 22.3 km rather than surging. If you don't know your current threshold, run the numbers through the FTP estimator before you commit to a target. On the steepest pitches, let your power drift above threshold only briefly, then settle back down the moment the grade relaxes toward 6.83%. Climbs like this reward the rider who finishes strong, not the one who leads early.

Gearing

With an average of 6.83% and spikes to 18.08% arriving after nearly an hour of climbing, gear low and gear generously. A compact crankset is essential. A 34×32 will get most fit riders up the sustained sections, but on a climb this long the extra sprocket of a 34×34 buys a meaningful cadence margin when the 18.08% ramps bite and your legs are 1524 m into the effort. If your bike and derailleur can accommodate it, favor the 34×34 — the ability to spin rather than grind late on a 22.3 km climb protects both your knees and your finishing power.

Summary

Passo Tratto Spino is a true HC test of endurance: long, relentless, and punctuated by ramps steep enough to break a poorly paced effort. Respect the distance, gear low, and hold your threshold steady from 201 m all the way to the 1725 m summit.

Length: 22.3 km
Average gradient: 6.83%
Max gradient: 18.08%
Start: 201 m
Summit: 1725 m
Net gain: 1524 m
Total ascent: 1617 m
Category: HC